Bangladeshi-origin MPs Rushanara Ali and Rupa Huq and their Pakistani-origin colleagues Afzal Khan and Mohammad Yasin are the four Labour party MPs to receive the same kind of package in their parliamentary offices within the Palace of Westminster over the last two days.

“It is worrying that these things are getting through security screening because I know it’s very vigorously screened. Someone out there thinks it is open season on Muslims,” said Huq, who represents Ealing central and Acton in south-west London.

One of her staff members who was hospitalised after coming in contact with the package has since been released. On Monday, two staff members from Yasin’s office had also been briefly hospitalised as a precautionary measure.

A parliamentary spokesperson said on Tuesday that two items of mail containing suspicious substances were investigated by the Metropolitan Police and were not found to be hazardous.